Heating the water for your daily shower can cost a surprising amount of money. We’ve calculated the costs for a standard electric water-cylinder, natural gas (storage and instant), LPG (storage and instant), heat-pump water heaters and woodburner wetbacks.
We've assumed that a 10-minute shower running at 8 litres of water per minute uses 40 litres of hot water (the shower being half hot and half cold water). So the costs in our table are to heat 40 litres of water from 10°C to 60°C.
Guide to the table
Electricity and natural gas costs are from PowerSwitch. Other costs are from pricing data collected during February 2011. GST is included.
Water-heating options
A woodburner wetback is the cheapest option. Our figures are for bought firewood – but free firewood is … well … free. A heat-pump water heater is the next cheapest option.
Electricity, natural gas and LPG are the most common options for water heating and the costs are close. Natural gas is slightly cheaper – apart from that, your best option depends on the cost of the various alternatives in your area.
Instant natural gas and instant LPG water-heating are both slightly cheaper than the storage versions because they don't have heat losses from the cylinder.
Solar water-heating
We haven't included solar because every installation is different and we don't have enough reliable data to make a call on running costs. But our best guess (depending on your location) is that running costs for solar water heating will be similar to heat-pump water heaters.
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